Swan T M, Watson K
School of Biological Sciences, University of New England, Armidale, Australia.
Can J Microbiol. 1999 Jun;45(6):472-9. doi: 10.1139/w99-033.
The response of a yeast unsaturated fatty acid auxotroph, defective in delta 9-desaturase activity, to heat and ethanol stresses was examined. The most heat- and ethanol-tolerant cells had membranes enriched with oleic acid (C18:1), followed in order by cells enriched with linoleic (C18:2) and linolenic (C18:3) acids. Cells subjected to a heat shock (25-37 degrees C for 30 min) accumulated trehalose and synthesized typical heat shock proteins. Although there were no obvious differences in protein profiles attributable to lipid supplementation of the mutant, relative protein synthesis as determined by densitometric analysis of autoradiograms suggested that hsp expression was different. However, there was no consistent relationship between the synthesis of heat shock proteins and the acquisition of thermotolerance in the lipid supplemented auxotroph or related wild type. Furthermore, trehalose accumulation was also not closely related to stress tolerance. On the other hand, the data presented indicated a more consistent role for membrane lipid composition in stress tolerance than trehalose, heat shock proteins, or ergosterol. We suggest that the sensitivity of C18:3-enriched cells to heat and ethanol may be attributable to membrane damage associated with increases in membrane fluidity and oxygen-derived free radical attack of membrane lipids.
研究了一种在Δ9-去饱和酶活性方面存在缺陷的酵母不饱和脂肪酸营养缺陷型对热应激和乙醇应激的反应。耐热性和耐乙醇性最强的细胞其细胞膜富含油酸（C18:1），其次依次是富含亚油酸（C18:2）和亚麻酸（C18:3）的细胞。经历热休克（25 - 37摄氏度，30分钟）的细胞积累了海藻糖并合成了典型的热休克蛋白。尽管由于对突变体进行脂质补充而导致的蛋白质谱没有明显差异，但通过对放射自显影片进行光密度分析所确定的相对蛋白质合成表明热休克蛋白的表达有所不同。然而，在脂质补充的营养缺陷型或相关野生型中，热休克蛋白的合成与耐热性的获得之间没有一致的关系。此外，海藻糖的积累也与应激耐受性没有密切关系。另一方面，所呈现的数据表明，与海藻糖、热休克蛋白或麦角固醇相比，膜脂组成在应激耐受性方面发挥着更为一致的作用。我们认为，富含C18:3的细胞对热和乙醇的敏感性可能归因于与膜流动性增加以及膜脂的氧衍生自由基攻击相关的膜损伤。
